The invention relates to a fuel supply system for an internal combustion engine with a fuel supply line extending from a fuel tank to a fuel injection device of the internal combustion engine and including a water separator and water discharge arrangement for discharging the water into the engine exhaust system.
The use of fuel filters with water separators in the fuel supply pipe to the fuel injection device of an internal combustion engine has been known for a long time. The water must thereby be regularly emptied from the fuel filter or the water separator. A problem here is that the water separated in the fuel filter is generally contaminated with fuel. Since non-combusted fuel may not be discharged into the environment, high-resource and costly water filters or treatment systems for example must be used for the disposal of the collected water.
DE 195 45 133 A1 discloses a fuel filter with a fuel inlet for the unpurified fuel and a fuel outlet for the purified fuel. Furthermore a water separator is integrated into the fuel filter, the water removal means of which is coupled with the fuel outlet. In order to mix a defined portion of fuel back into the separated water flow the removal pipe of the water separator is coupled with the fuel pipe connected to the fuel outlet in such a way that the desired fuel-water ratio is set via defined throttle points of a mixer unit. In order to promote a lower pressure gradient with equal mixing function the mixer unit with its throttle points may be in the form of Venturi nozzles.
It is further known for example from DE 10 2006 027 201 A1 to inject the water separated in the fuel filter—including the fuel contained therein—via an injection nozzle into the exhaust gas system of the internal combustion engine. The injection of the water into the exhaust gas system however can lead to thermal problems in the exhaust gas after-treatment process, as the water concentration can fluctuate very greatly and unpredictably in the range from 0 to 100%.
It is the principal object of the present invention to provide an improved fuel supply system with a fuel filter including means for collecting the water separated from the fuel and disposing the water in an environmentally friendly and reliable process.